Problem: A bag contains $10$ red jelly beans, $11$ green jelly beans, and $10$ blue jelly beans. If a jelly bean is randomly chosen, what is the probability that it is not blue?
There are $10 + 11 + 10 = 31$ jelly beans in the bag. There are $10$ blue jelly beans. That means $31 - 10 = 21$ are not blue. The probability is $ \frac{21}{31}$.